可调扩压器端隙控制对离心压气机性能影响

Diffuser Endwall Clearance Mitigation and Its Influence on the Performance of Variable Geometry Centrifugal Compressor

在飞机飞行包线内,高速电机直驱可调离心压气机可通过扩压器调节以满足飞行工况下客舱增压系统的供气需求,并使压气机始终工作在高效区,从而满足飞机客舱环境的舒适性并降低增压系统能耗。对于可调扩压器,扩压器叶片两侧存在端隙。在扩压器叶片高度较小的情况下,较大的隙高比导致扩压器内端隙泄漏严重,给压气机性能带来较大的负面影响。以抑制可调扩压器端隙泄漏、提高压气机效率为目的,本文首先分析了扩压器端隙对压气机性能的影响,在此基础上,设计了一种将扩压器叶片端部部分封闭从而改变端隙泄漏路径的整体式可调扩压器结构,研究了该扩压器结构对于端隙泄漏的抑制效果以及对可调压气机性能的改善幅度。结果表明,相对于传统可调扩压器,整体式扩压器结构可有效抑制可调扩压器叶片端隙泄漏损失并提高可调压气机效率。对于本文所研究的可调压气机,峰值效率可提升1.1%,对应压比可提升1.3%。

The variable geometry compressor(VGC)driven by the high speed electric motor can match the air supply requirements of the airplane cabin within the whole flight envelop.Meanwhile,it can enable the compressor to work in high efficiency region and decrease the power consumption of the cabin pressurization system.The clearances between the vane tips and diffuser walls are necessary for the variable vane diffuser to operate.Because of the small height of the diffuser vane,the vane clearance-to-height ratio is relatively large and leads to strong side clearance leakage loss,which brings significant negative influence on the compressor performances.In order to suppress the side-gap leakage flow in the variable vane diffuser and improve the compressor efficiency,the influence of the diffuser side-gap leakage on the compressor performance was investigated and a pedestal-mounted variable vane structure was developed.By alternating the flow path of the sidegap leakage flow,the benefits of the new vane structure on the side-gap leakage suppression and compressor performance improvement were investigated.Results indicate that the new variable diffuser can effectively suppress the side-gap clearance leakage loss and improve the efficiency of the VGC compared to the traditional full side-gap VGC.For the VGC investigated in current study,the peak efficiency was increased by 1.1%and the corresponding pressure ratio was increased by 1.3%.